[PATCH net-next v4 3/8] netconsole: Helper to count number of used entries

[Breno Leitao <leitao@debian.org>]

Add a helper function nr_extradata_entries() to count the number of used
extradata entries in a netconsole target. This refactors the duplicate
code for counting entries into a single function, which will be reused
by upcoming CPU sysdata changes.

The helper uses list_count_nodes() to count the number of children in
the userdata group configfs hierarchy.

Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Simon Horman <horms@kernel.org>
---
 drivers/net/netconsole.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index 15867bb481e226cbb4164642e470baecca730a40..bfcc3809f4b5fa351c8e7e6340a54e93d525aa2e 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -662,6 +662,16 @@ static ssize_t remote_ip_store(struct config_item *item, const char *buf,
 	return ret;
 }
 
+/* Count number of entries we have in extradata.
+ * This is important because the extradata_complete only supports
+ * MAX_EXTRADATA_ITEMS entries. Before enabling any new {user,sys}data
+ * feature, number of entries needs to checked for available space.
+ */
+static size_t count_extradata_entries(struct netconsole_target *nt)
+{
+	return list_count_nodes(&nt->userdata_group.cg_children);
+}
+
 static ssize_t remote_mac_store(struct config_item *item, const char *buf,
 		size_t count)
 {
@@ -811,15 +821,13 @@ static struct config_item *userdatum_make_item(struct config_group *group,
 	struct netconsole_target *nt;
 	struct userdatum *udm;
 	struct userdata *ud;
-	size_t child_count;
 
 	if (strlen(name) > MAX_EXTRADATA_NAME_LEN)
 		return ERR_PTR(-ENAMETOOLONG);
 
 	ud = to_userdata(&group->cg_item);
 	nt = userdata_to_target(ud);
-	child_count = list_count_nodes(&nt->userdata_group.cg_children);
-	if (child_count >= MAX_EXTRADATA_ITEMS)
+	if (count_extradata_entries(nt) >= MAX_EXTRADATA_ITEMS)
 		return ERR_PTR(-ENOSPC);
 
 	udm = kzalloc(sizeof(*udm), GFP_KERNEL);

-- 
2.43.5